Repost: Colourblinded by the Light

[note: Here's a throwback to fill in some time while I move --
originally published in 2014, I talk about colourblindness and making
sure that you're communicating in the most accessible way. Enjoy!]

Originally published September 25th, 2014
Graphs
are necessary in most academic papers. They are one of the best ways to
show the data collected and illustrate relationships (or lack thereof)
and support to the conclusions of the study. They also wreak havoc on a
lot of authors and students -- what is the best way to show my modelled
data? Bar graph? Scatterplot? Do I attempt a donut graph just to see if I
can get away it it (hint: you can't).

Published
online at PLoS Computational Biology just two weeks ago, Rougier et al's
"Ten Simple Rules for Better Figures" has gained a lot of press and
popularity, and for good reason[1]. The format of an online-only
open-access journal like those in the PLoS collection benefit this
article for two reason: First, the authors were able to display
remarkable graphs in full colour alongside an easy-to-understand
narrative. Second, they are not limited by distribution rights and and
their audience is not hindered lack of access.

I
won't break down all ten rules, but one in particular got me thinking
about the accessibility of my own figures. Rule 6 is to Use Color
Effectively, and ends with, "Lastly, avoid using too many similar
colo[u]rs since color blindness may make it difficult to discern some
colo[u]r differences." This includes a reference to Masataka Okabe and
Kei Ito's page on the University of Tokyo's Drosophila research
group: "Color Universal Design (CUD) - How to make figures and
presentations that are friendly to colo[u]rblind people." [2]

While the prevalence of colourblindness varies among ethnic groups and
between sexes, the figures worldwide indicate that around 7.0% of the
males and 0.4% of females are red-green colourblind, and a very small
percentage are blue-yellow colourblind[3]. Those with red-green
colourblindness are said to have either protanope vision (reduced
sensitivity to red) or deuteranope vision (reduced sensitivity to
green), depending on the cone cells affected. Blue-yellow
colourblindness is a reduced sensitivity to blue light and the
individual is said to have tritanope vision[4]. Within these catergories
are variation based on the amount of working cones individuals possess.
Okabe and Ito go into great detail about the different ways that
colourblind individuals may be left out of scientific discussion when it
comes to the colours of graphs, presentations, and stains. I feel that
the staining is the most important - if you're working with fluorescent
double-staining, the most commonly used stains are green and red, a
sharp contrast for non-colourblind individuals, but end up blending
together for those with red-green colourblindness. You can read about this and more, including the 3(+1) principles of universal colour design, on the CUD page.

This is all interesting to me, but you may wonder what it has to do
with my research. Well, I'm studying the effects of different colours of
artificial lights at night affect bat behaviour - white (nearly-full
spectrum), green, and red. And when it comes time to make my graphs, I
use colour in addition to labels to indicate the different treatments. I
never really considered the properties of my graph colours - I just
want them to look nice. But looking at the examples presented by Okabe
and Ito, I became intrigued. What if my graphs are not legible or
aesthetic to someone despite my best intentions? Luckily, there's a way
to see through the eyes of someone with colourblindness, or at least to
view images with an appropriate filter.

I use
ImageJ for my research, and there is a plug-in called VisCheck that is
easy to install and use[5]. Five minutes, and I was staring at a glaring
issue. I originally went for an orangey-red and a yellowish-green, a
palette I love. However, under the filters for each condition, they
looked very similar. Too similar. While my groups have written labels as
well, it's good that I checked this now before going on with my more
complicated graphs. I've made a few example graphs that look like the
data I'm working with and ran them through VisCheck (my actual graphs
were a bit worse when filtered).

There may be those who would argue that I likely won't have someone who
is colourblind at my defense. I likely won't publish my work in a
journal that supports full colour graphs. That being said, while I'm not
colourblind, that shouldn't stop me from making sure that the way I
communicate is inclusive. Knowledge needs to be accessible to those that
wish to gain from it. Textbook publishers have addressed this, and so
should scientists, journal publishers, and educators. The tools are out
there, they just need to be advocated for and used.

Back to my research, I'm left with on question that I have yet to find
an answer to: if red or green light is recommended for large-scale use
outdoors, how does that affect those with red-green colourblindness? [note: I still don't know the answer to this! KF 2016]

PhD candidate at the Wageningen University in The Netherlands; Canadian
by birth, former German resident for 3 years, current Dutch resident by permit; enthusiast of science, ecology, biocontrol,
conservation, intersectional feminism, interdisciplinary works,
geocaching, and sustainable tourism.
BSc Biological Sciences, University of Alberta '12MSc Ecology, University of Bremen '15